1. Technical Field
The present disclosure relates generally to the field of inspection and reconditioning of tubular goods such as sucker rods, and more specifically to methods of sorting used tubular goods prior to exposing the goods to reconditioning processes.
2. Background Art
Sucker rod is used as an example in the following discussion, but the methods are applicable to other tubular goods, such as production tubing, line pipe, and the like. It is assumed the reader is familiar with sucker rods and their use. As will be noted, the process involves many steps and it is an object of the present disclosure to pre-sort the rods so that only those rods worthy of returning to use are subjected to all of the steps.
Referring to FIG. 1, in convention methods, at a well site 2 or other site where used sucker rod is to be picked up for reclaiming or reconditioning (the difference between reclaiming and reconditioning is explained below), rods are loaded onto trucks using support stripping to prevent bending. In areas where multiple wells 2 are to be picked up, within short distance of a reconditioning plant, truck trailers having specially developed cranes may be used. After the used rods arrive at a plant 4 (indicated by dashed line box) they are lifted to a holding area 6 where they are uniquely identified according to size, quantity, company name and well location and tagged appropriately. This identity is maintained throughout the entire inspection and reconditioning process. In conventional methods, all used rods are then dipped in a hot kerosene bath 8 to remove paraffin, grease and other foreign materials. Once the used rods are clean, they are normally all moved into the plant 4, where the reconditioning or reclaiming process begins.
Visual inspection 10 is the first step in the convention reclamation and reconditioning processes. Visual inspection involves a human visually locating pitting, corrosion, wear, stretched rods and bent rods. Any rod failing to pass this visual inspection is temporarily removed from the plant. Any rods that are bent, bowed, or have rod guides on them are removed and sent to a rod straightening machine 12 and/or a rod guide removal machine 14. Once they are straight and have the rod guide removed, they are all returned to the plant 4 for the reconditioning or reclaiming process. From experience, one might surmise that some of these straightened and cleaned used rods might have unseen defects (cracks, for example), and that some of these defects may in fact make those rods unacceptable for their intended field use, but all the rods are nevertheless processed in the plant until a defect is found. In a typical plant 4, the next step 16 is for all couplings to be removed; in some cases this may be accomplished with a specially designed hydraulic device. Pin end areas are buffed and cleaned to parent metal. Once the pins are cleaned they are inspected and gauged. Any rod that is rejected in step 16 is removed from plant 4, as indicated by box 18, only after much effort and expense.
In reclaiming or reconditioning used sucker rod, rust, scale and other surface materials are removed by shot cleaning or shot peening 20. Shot peening defines reconditioning as opposed to simply reclaiming rods. Shot peening has been shown to increase the life of used rod from 50 to 100 percent. After exiting the shot cleaner or shot peener 20 the rod may pass through a magnetic normalizing device 24. Typically, used rods have a residual magnetic field in the body of the rod. This magnetic field is not consistent within the lot to be reconditioned. The magnetic inconsistency has a dramatic effect on Eddy Current inspection, causing inaccurate results. By creating a consistent magnetic field in the rod prior to Eddy Current inspection, consistent, reliable inspection results are achieved. Magnetic normalization increases the likelihood of flaw detection, and thereby greatly reduces the likelihood of a sucker rod failure caused by localized stress, fatigue, and improper normalization of the upset run out. Once the rod is either shot cleaned or shot peened, and after any magnetic normalization, it is full length inspected by an Eddy Current Device 26. This device identifies fatigue, embrittlement and irregular normalizing in the rod body. In some plants, any rejected rods are removed from plant 4, as indicated at box 28. It should be mentioned here that the use of symbols (boxes, circles, etc.) in the various figures is completely arbitrary unless specifically pointed out. Dashed boxes indicate optional processes, or processes that some plants may not practice.
Depending on the particular plant, rods to be further reclaimed or reconditioned may then progress into a rotating laser measurement unit 30 where the entire rod may be examined to determine if it is within diameter specifications. Rods to be further reclaimed or reconditioned then are passed into an EMI (electromagnetic inspection) unit 34 where injurious pits and cracks are identified. End areas of rods that remain acceptable are subjected to wet magnetic particle inspection, as indicated by box 38. Wet magnetic particle inspection detects cracks in the thread area, undercut area, wrench flat area, upset, and transition area. Liberal amounts of corrosion inhibitor lubricant and a new protector is applied to end areas of rods that remain acceptable after end area inspection station 38. The sucker rod is then run through a device 42 that removes the residual magnetic field in the rod that was induced for inspection purposes to an acceptable level. An amine-based corrosion inhibitor is typically applied at station 44, which will provide corrosion protection during storage, and approximately two weeks downhole protection. Each rod is color coded as to the final grade of the reclaimed or reconditioned rod. After the rod has been coded, it is removed from the plant 4 and placed into storage 46 for inventory control.
As noted, both reclaiming and reconditioning processes involve many steps, materials, manpower, and plant space. Most plants have no or minimal ways of getting rejects out of the plant that fail. This is a real problem addressed by the present disclosure; if rejects could be denied entry to the plant, then all of the processes being performed in the plant would be performed on acceptable material and not sub-standard material. These processes cost money and if the money is only being spent on acceptable products, then that is the most cost effective manner in which to operate the plant. This is an important issue; in many instances the ability to remove a product at the point of rejection in a reclamation or reconditioning plant is materially overstated. A problem with both reconditioning and reclaiming sucker rods and other tubulars is that the visual inspection 10 is not reliable and often fails to identify tubulars that are ultimately, after passing through many of the above-described steps, rejected. The result is a waste of time, materials, and plant space for those rods that are ultimately rejected.
The industry has long lived with the above-mentioned problem and has accepted it as a fact of the business. There is thus a long-felt but as yet unmet need in the art of reconditioning and reclaiming tubulars, and in particular sucker rod, for an effective method of solving this problem.